3rd-party/libtins
1
0
Fork 0
mirror of https://github.com/mfontanini/libtins synced 2026-01-23 02:35:57 +01:00
Code Issues Releases Wiki Activity

Fixed TCP checksum. Documented pdu.h.

Browse Source
This commit is contained in:
Matias
2011-08-12 20:17:21 -03:00
parent d59cec94b6
commit 2cdf0f6b29
7 changed files with 124 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
include/ip.h
View File

@@ -164,12 +164,11 @@ namespace Tins {
static const uint8_t DEFAULT_TTL;
void init_ip_fields();
void write_serialization(uint8_t *buffer, uint32_t total_sz);
void write_serialization(uint8_t *buffer, uint32_t total_sz, PDU *parent);
iphdr _ip;
std::vector<IpOption> _ip_options;
uint32_t _options_size;
uint32_t _padded_options_size;
uint32_t _options_size, _padded_options_size;
};
};

84
include/pdu.h
View File

@@ -30,37 +30,95 @@ namespace Tins {
class PacketSender;
/** \brief PDU is the base class for protocol data units.
*
* Every PDU implementation must inherit this one. PDUs can be serialized,
* therefore allowing a PacketSender to send them through sockets. PDUs
* are created upwards: upper layers will be children of the lower ones.
* Each PDU must provide its flag identifier. This will be most likely added
* to its parent's data, hence it should be a valid identifier. For example,
* IP should provide IPPROTO_IP.
*/
class PDU {
public:
/** \brief PDU constructor
*
* Must be called by subclasses in their constructors.
* \param flag The flag identifier for the subclass' PDU.
* \param next_pdu The child PDU. Can be obviated.
*/
PDU(uint32_t flag, PDU *next_pdu = 0);
virtual ~PDU();
/* This PDU's header size only. */
/** \brief The header's size
*/
virtual uint32_t header_size() const = 0;
/* This PDU's trailer size only. Defaults to 0. */
/** \brief Trailer's size.
*
* Some protocols require a trailer(like Ethernet). This defaults to 0.
*/
virtual uint32_t trailer_size() const { return 0; }
/* The size of the whole chain of PDUs, including this one. */
inline uint32_t size() const;
/** \brief The whole chain of PDU's size, including this one.
*
* Returns the sum of this and all children PDUs' size.
*/
uint32_t size() const;
/** \brief This PDU's type flag identifier.
*
*/
inline uint32_t flag() const { return _flag; }
/** \brief The child PDU.
*/
inline const PDU *inner_pdu() const { return _inner_pdu; }
/** \brief Sets the flag identifier.
*/
void flag(uint32_t new_flag);
/* When setting a new inner_pdu, the instance takes
* ownership of the object, therefore deleting it when
* it's no longer required. */
/** \brief Sets the child PDU.
*
* \param next_pdu The new child PDU.
* When setting a new inner_pdu, the instance takesownership of
* the object, therefore deleting it when it's no longer required.
*/
void inner_pdu(PDU *next_pdu);
/* Serializes the whole chain of PDU's, including this one. */
/** \brief Serializes the whole chain of PDU's, including this one.
*
* \param sz The size of the buffer must be returned through this parameter.
* The buffer returned must be deleted by the user using
* operator delete[].
*/
uint8_t *serialize(uint32_t &sz);
/* */
virtual bool send(PacketSender* sender) {return false;}
/** \brief Send the stack of PDUs through a PacketSender.
*
* This method will be called only for the PDU on the bottom of the stack,
* therefore it should only implement this method if it can be sent.
* PacketSender implements specific methods to send packets which start
* on every valid TCP/IP stack layer; this should only be a proxy for
* those methods.
* \param sender The PacketSender which will send the packet.
*/
virtual bool send(PacketSender* sender) { return false; }
protected:
/* Serialize this PDU storing the result in buffer. */
void serialize(uint8_t *buffer, uint32_t total_sz);
void serialize(uint8_t *buffer, uint32_t total_sz, PDU *parent);
/* Each PDU's own implementation of serialization. */
virtual void write_serialization(uint8_t *buffer, uint32_t total_sz) = 0;
/** \brief Serialices this TCP PDU.
*
* Each PDU must override this method and implement it's own
* serialization.
* \param buffer The buffer in which the PDU will be serialized.
* \param total_sz The size available in the buffer.
* \param parent The PDU that's one level below this one on the stack. Might be 0.
*/
virtual void write_serialization(uint8_t *buffer, uint32_t total_sz, PDU *parent) = 0;
private:
uint32_t _flag;
PDU *_inner_pdu;

16
include/tcp.h
View File

@@ -185,12 +185,6 @@ namespace Tins {
* payload and options size.
*/
uint32_t header_size() const;
/** \brief Serialices this TCP PDU.
* \param buffer The buffer in which the PDU will be serialized.
* \param total_sz The size available in the buffer.
*/
void write_serialization(uint8_t *buffer, uint32_t total_sz);
private:
struct tcphdr {
uint16_t sport;
@@ -239,7 +233,15 @@ namespace Tins {
static const uint16_t DEFAULT_WINDOW;
uint16_t do_checksum(uint8_t *start, uint8_t *end) const;
/** \brief Serialices this TCP PDU.
* \param buffer The buffer in which the PDU will be serialized.
* \param total_sz The size available in the buffer.
* \param parent The PDU that's one level below this one on the stack.
*/
void write_serialization(uint8_t *buffer, uint32_t total_sz, PDU *parent);
uint32_t do_checksum(uint8_t *start, uint8_t *end) const;
uint32_t pseudoheader_checksum(uint32_t source_ip, uint32_t dest_ip) const;
tcphdr _tcp;
std::vector<TCPOption> _options;

3
src/ip.cpp
View File

@@ -54,6 +54,7 @@ void Tins::IP::init_ip_fields() {
_ip.ihl = sizeof(iphdr) / sizeof(uint32_t);
_ip.ttl = DEFAULT_TTL;
_options_size = 0;
_padded_options_size = 0;
}
/* Setters */
@@ -166,7 +167,7 @@ bool Tins::IP::send(PacketSender* sender) {
return sender->send_l3(this, (const struct sockaddr*)&link_addr, sizeof(link_addr));
}
void Tins::IP::write_serialization(uint8_t *buffer, uint32_t total_sz) {
void Tins::IP::write_serialization(uint8_t *buffer, uint32_t total_sz, PDU *) {
uint32_t my_sz = header_size();
uint32_t new_flag;
assert(total_sz >= my_sz);

1
src/packetsender.cpp
View File

@@ -77,6 +77,7 @@ bool Tins::PacketSender::send_l3(PDU *pdu, const struct sockaddr* link_addr, uin
int sock = _sockets[IP_SOCKET];
uint8_t *buffer = pdu->serialize(sz);
ret_val = (sendto(sock, buffer, sz, 0, link_addr, len_link_addr) != -1);
std::cout << "Ret_val: " << ret_val << "\n";
delete[] buffer;
}

8
src/pdu.cpp
View File

@@ -52,16 +52,16 @@ void Tins::PDU::inner_pdu(PDU *next_pdu) {
uint8_t *Tins::PDU::serialize(uint32_t &sz) {
sz = size();
uint8_t *buffer = new uint8_t[sz];
serialize(buffer, sz);
serialize(buffer, sz, 0);
return buffer;
}
void Tins::PDU::serialize(uint8_t *buffer, uint32_t total_sz) {
void Tins::PDU::serialize(uint8_t *buffer, uint32_t total_sz, PDU *parent) {
uint32_t sz = header_size() + trailer_size();
/* Must not happen... */
assert(total_sz >= sz);
if(_inner_pdu)
_inner_pdu->serialize(buffer + header_size(), total_sz - sz);
write_serialization(buffer, total_sz);
_inner_pdu->serialize(buffer + header_size(), total_sz - sz, this);
write_serialization(buffer, total_sz, parent);
}

41
src/tcp.cpp
View File

@@ -21,10 +21,12 @@
#include <cstring>
#include <cassert>
#include <iostream> //borrame
#ifndef WIN32
#include <netinet/in.h>
#endif
#include "tcp.h"
#include "ip.h"
#include "utils.h"
@@ -125,10 +127,28 @@ void Tins::TCP::add_option(Options tcp_option, uint8_t length, uint8_t *data) {
_total_options_size = (padding) ? _options_size - padding + 4 : _options_size;
}
uint16_t Tins::TCP::do_checksum(uint8_t *start, uint8_t *end) const {
unsigned checksum(0);
while(start < end)
checksum += *(start++);
uint32_t Tins::TCP::do_checksum(uint8_t *start, uint8_t *end) const {
uint32_t checksum(0);
uint16_t *ptr = (uint16_t*)start, *last = (uint16_t*)end, padding(0);
if(((end - start) & 1) == 1) {
last = (uint16_t*)end - 1;
padding = *(end - 1) << 8;
}
while(ptr < last)
checksum += Utils::net_to_host_s(*(ptr++));
return checksum + padding;
}
uint32_t Tins::TCP::pseudoheader_checksum(uint32_t source_ip, uint32_t dest_ip) const {
uint32_t checksum(0), len(header_size());
source_ip = Utils::net_to_host_l(source_ip);
dest_ip = Utils::net_to_host_l(dest_ip);
uint16_t *ptr = (uint16_t*)&source_ip;
checksum += *ptr + ptr[1];
ptr = (uint16_t*)&dest_ip;
checksum += *ptr + ptr[1];
checksum += IPPROTO_TCP + len;
return checksum;
}
@@ -136,7 +156,7 @@ uint32_t Tins::TCP::header_size() const {
return sizeof(tcphdr) + _payload_size + _total_options_size;
}
void Tins::TCP::write_serialization(uint8_t *buffer, uint32_t total_sz) {
void Tins::TCP::write_serialization(uint8_t *buffer, uint32_t total_sz, PDU *parent) {
assert(total_sz >= header_size());
uint8_t *tcp_start = buffer;
buffer += sizeof(tcphdr);
@@ -153,7 +173,16 @@ void Tins::TCP::write_serialization(uint8_t *buffer, uint32_t total_sz) {
}
memcpy(buffer, _payload, _payload_size);
_tcp.check = Utils::net_to_host_s(do_checksum(tcp_start + sizeof(tcphdr), buffer));
buffer += _payload_size;
IP *ip_packet = dynamic_cast<IP*>(parent);
if(ip_packet) {
_tcp.check = 0;
uint32_t checksum = pseudoheader_checksum(ip_packet->source_address(), ip_packet->dest_address()) +
do_checksum(tcp_start + sizeof(tcphdr), buffer) + do_checksum((uint8_t*)&_tcp, ((uint8_t*)&_tcp) + sizeof(tcphdr));
while (checksum >> 16)
checksum = (checksum & 0xffff)+(checksum >> 16);
_tcp.check = Utils::net_to_host_s(~checksum);
}
memcpy(tcp_start, &_tcp, sizeof(tcphdr));
}